People receiving a renal transplant require long-term treatment with immunosuppressant drugs. Contemporary regimens usually include a calcineurin inhibitor (CI), either ciclosporin or tacrolimus, in conjunction with at least one other drug. The aim of this study was to review the economic literature relating to the choice of CIs in patients following renal transplantation, with the specific intention of highlighting the challenges in estimating their cost effectiveness.A systematic literature search and narrative analysis was carried out, and 12 studies of varying quality and complexity were reviewed. All of the studies compared ciclosporin, azathioprine and a corticosteroid (CAS) with tacrolimus, azathioprine and a corticosteroid (TAS) but only three also evaluated the costs and effects of other possible treatment regimens. A variety of different evaluative frameworks were employed, from single randomised controlled trial-based studies over relatively short-time periods (6 months) to more complex Bayesian modelling techniques.The studies were broadly consistent in concluding that TAS was more effective than CAS in terms of reducing the rate of acute rejection episodes. Of the studies that undertook decision modelling, all but one estimated that TAS was associated with better graft-related outcomes such as rejection-free life-years, patient-survival and QALYs. Six of the studies concluded that the healthcare costs associated with TAS were lower than those for CAS. A seventh study suggested that TAS was the least costly option if costs were considered over a relatively long time period (14 years). Only one study clearly concluded that CAS was more cost effective than TAS.Clinical evidence clearly shows that TAS is more effective than CAS in terms of reducing the incidence of acute rejection following renal transplantation. The majority of published economic evaluations suggest that TAS is also the more cost-effective option. However, the economic evaluations contained a number of methodological limitations, undermining the confidence that can be attached to their results. Future economic evaluations of the CIs, and immunosuppressants in general, should address these issues in order to produce more robust cost-effectiveness estimates. Most importantly, they should evaluate a wider range of potential treatment options.